Impact fuse for projectiles



Nov. 12, 1968 R. APOTHEILOZ 3,410,215

IMPACT FUSE FOR PROJECTILES Filed June 20, 1967 4 Sheets-Sheet 1 Nov. 12, 1968 R. APOTHE LOZ IMPACT FUSE FOR PROJECTILES 4 Sheets-Sheet 2 Filed June 20, 1967 Q o oW 4 1 v0.0.0,? rammlullflillli 1 v ilk I LIL 4 Ill 3&2 I000? .rtbibs 'IIIIIIIII, 11]! x w m vm 9 Nov. 12; 1968 APOTHE/LOZ 3,410,215

IMPACT FUSE FOR PROJEC'IILES Filed June 20, 1967 4 Sheets-Sheet 3 I5 Ann mlllluk Nov. 12, 1968 R. APOTHE LOZ IMPACT FUSE FOR PROJECTILES Filed June 20. 1967 4 Sheets-Sheet 4 I will!!! A 6 3 3.3. /flaw 1 76 w l PM"... lure F m:o mI Z 'k' y u'flallm m MA", 8 s \Qlll' W MW 1 5 fi a .i m v a 7 3 2 a I 3 1 2 I 5 0 l4 W W 5 5 5 5 B m m m m y a a x a! 1 y n 4 a 7 1+ 0 2 I 0 7 6 MNMN .g 2 MW 1+ 3 1+ 1+ 1+ 1+ 1+ 8 H 1+ 1+ United States Patent IMPACT FUSE FOR PROJECTILES Robert Apotheloz, Wallisellen, Switzerland, assignor to Oerlikon-Buhrle Holding Ltd., Zurich, Switzerland Filed June 20, 1967, Ser. No. 647,521 Claims priority, application Switzerland, June 21, 1966, 8,975/66 4 Claims. (Cl. 10278) ABSTRACT OF THE DISCLOSURE Mounted in an impact fuse for projectiles are two inertia members, one of which responds to a deceleration of the projectile in the axial direction and the other to a deceleration of the projectile transversely to the axial direction of the projectile. Through said two decelerations, two locking sleeves, which hold a striker pin in a locked position through locking members, are displaced into their forward position by the inertia members, and a spring is compressed which bears on the one hand against the striker pin and on the other hand against a locking sleeve. As soon as the deceleration ceases, the one locking sleeve is displaced into its initial position under the force of the spring and the striker pin is released for the firing.

This invention relates to impact fuses for projectiles.

An object of the invention is to provide an impact fuse which responds in the event of graze shots, such as when the projectile strikes the target at a very small angle or rebounds therefrom, the priming being delayed to such an extent that the detonation only takes place after the rebound.

With the above and other objects in view which will become apparent from the following detailed description below, two embodiments of the invention are shown in the drawings in which:

FIGURE 1 shows a partial axial section of a first embodiment through a point fuse in the secured position in which a device for the delayed detonation is in its initial position.

FIGURE 2 shows a similar view of a base fuse, of a second embodiment in the secured position.

FIGURE 3 is a sectional view of section line IIIIII in FIGURE 2.

FIGURE 4 shows an axial section through the device for the delayed detonation for the striker pin, which is of the same construction in both examples, in the position immediately after the impact.

FIGURE 5 shows the same device as in FIGURE 4 after the release of the striker pin.

FIGURE 6 shows the same device as in FIGURE 4 at the moment of detonation, and

FIGURE 7 shows a section through the impact fuse on section line VII--VII in FIGURE 2.

Like parts are designated by the same reference numerals in both embodiments. In order to avoid repetition, both embodiments are described partly at the same time.

According to FIGURE 1, a fuse casing 1 for a nonrotating projectile, for example a mortar projectile, is screwed to a warhead 2 and carries a booster at its rear end. A guide 7 which is inserted in the fuse casing 1 is providedwith a groove 8 which is rectangular in crosssection' and directed transversely to the fuse axis and in which there is mounted a prismatic slide 9. In one of two bores parallel with the axis of the fuse, the slide 9 contains a primer 11 and in the other bore 12 a primer 13 adapted for: contact from the rear. A spring 15, not illustrated, which bears against the fuse housing 1 and against the slide 9, tends to displace the slide 9 into the armed position. Before the firing, however, this is prevented by a locking sleeve 16 which is only illustrated for the ex- 3,410,215 Patented Nov. 12, 1968 ample shown in FIGURE 2 and which is mounted for displacement in a longitudinal bore in the fuse casing 1 and is urged forwards into its locking position by a spring not illustrated.

The slide 9 is connected to a delay mechanism which delays the displacement of the slide from its safety position into the armed position which leads to a certain bore safety of the fuse. Such a delay mechanism is described in the Swiss patent specification No. 360,927.

According to FIGURE 1, a powder train 26 which extends from the rear edge of the slide 9 to the booster 10 is inserted in a central longitudinal bore in the fuse casing 1, and a device for the delayed detonation is contained in a further bore 27 parallel to this.

According to FIGURE 4, a cylindrical member 34 which projects into the bore 27 comprises at its rear end an extension 35 which is directed transversely to its longitudinal axis and the lateral faces 36 (FIGURE 7) have a spacing which is equal to the diameter of the member 34 and the length of which is greater than the diameter of the bore 27. The front end of this member 34 is provided, over the whole circumference, with an annual groove 37 which is bounded towards the front by a chamfered surface 38. A sleeve 39, which is movable in the bore 27, is inverted over the member 34. Between the bore recess 40 in the sleeve 39 and the rear end of the striker pin 28 there is inserted a spring 41.

The front end of the member 34 projects into a bore 29 in the striker pin 28. This is coupled to and secured by the locking balls 42 which are contained in its bores 30 directed towards the axis and which are pressed against the chamfered surface 38 of the member 34 by the pressure of the spring 41. A sleeve 43, the bore of which has the same diameter as that of the bore of the front portion of the sleeve 39, bears with its faceted end face 44 against the end face of the sleeve 39.

Since the seleve 39 bears against a bush described below, the extension 35 is urged, under the action of the pressure exerted by the spring 41 on the member 34 through the locking members 42, against the bore recess forming the shoulder 46.

The rear, forked end 47 of the sleeve 39 engages over the extension 35 on the cylindrical member 34 and bears against the cover 48 of the bush 50 guided in a bore 49. Guided in this bush 50 is a further bush 51 to the bottom 52 of which there is connected a pin 53 which engages through an aperture in the cover 48 of the bush 50. A spring 55 which bears on the one hand against the bottom 52 of the bush 51 and furthermore against the cover 48 of the bush 50 urges the two bushes 50, 51 so far apart that a dog 56 which is connected to the pin 53 and is situated in front of the bush 50 bears against the cover 48 thereof.

The spring 41 (FIGURE 4), the force of which is less than that of the pressure of the spring 55 which is transmitted to the bush 51 through the rear end 47 of the inertial sleeve 39, through the bush 50 and the spring 55, urges the flange 52a of the bush 51 against an inertia member 57 constructed in the form of a ball. This inertia member 57 is mounted in a cavity 58 in the body 1 of the fuse, the front portion of which is a cylindrical cavity widened out in comparison with the bore 49. The cavity 58 comprises a tapered portion at the rear. The diameter of the cavity 58 is greater than the diameter of the inertia member 57 which bears against the tapered boundary surface of the cavity 58.

The mode of operation of the point fuse described as a first embodiment is as follows:

In the position of the fuse illustrated in FIGURE 1, the slide 9 is held in its unarmed position by the locking sleeve 16. When the fuse is in the unarmed position, the front narrowed portion 45 of the sleeve 43 extends beyond the slide 9. When the projectile carrying the fuse is fired, the locking of the locking sleeve 16 is released so that this releases the slide through its backward movement. Under the pressure of the leaf spring 15, the slide then slides with a velocity corresponding to the required bore safety, into the armed position in which the primer 13 comes to lie coaxially above the striker pin 28 (FIG- URE 4).

When the projectile strikes the target with a large angle of impact, the two sleeves 39 and 43 are thrown forwards, despite the braking force exerted successively by the locking members 42 on the sleeves 39 and 43 and against the force of the spring 41, under the action of the inertia forces acting on them themselves and the further inertia force of the inertia member 57 which is transmitted forwards to the sleeve 39 through the bushes 50 and 51 and which is added to these forces. At the end of this movement, when the shoulder on the sleeve 43 bears against the rear face of the slide 9, the joint between the two sleeves 39 and 43 is situated in front of the locking members 42. The spring 41 is still further tensioned by this movement of the sleeve 39 (FIGURE 4).

When the deceleration of the projectile, and hence of the fuse, has dropped to a low value, the spring 41 can move the sleeve 39 towards the rear so that the balls 42 can emerge from the annular groove 37 under the pressure of the reaction forces transmitted by the chamfered surface 38 on the member 34 and enter the space now forming between the sleeves (FIGURE As a result the striker pin 28 becomes free and is thrown forwards under the action of the spring 41. In the course of this, the balls 42 are guided inwards by the chamfered surface 44 on the sleeve 43 into the bore 29 in the striker pin so that this now travels unhindered until it strikes the sleeve 43 and contacts the primer 13 through the bore 12 (FIG- URE 6). When the slide 9 is in the armed position, this primer is in spatial communication, through the groove 7a machined in the guide 7, with the primer 11 and fires this as a result of which the booster is caused to detonate through the powder train 26.

When the projectile strikes obliquely, for example when it ricochets on the ground with a very small angle of impact and so is subjected to a great acceleration which acts in the direction of the arrow F (FIGURE 1) and is directed transversely to the axis and which is initially negative and then positive, the inertia member 57 is thrust forwards by a reaction force transmitted from the tapered surface 60 of its guide, during its lateral displacement effected under the action of the inertia force acting thereon. During this movement, it pushes the bushes 50 and 51, and hence also the inertial sleeves 39 and 43 in front of it to such an extent that the joint between the sleeves lies in front of the locking members 42 so that the detonation process already described is initiated (FIGURES 4 and 5). When the acceleration directed transversely to the axis of the projectile has dropped to that value at which the detonation can take place, the sleeve 39 together with the bushes 50, 51 and the inertia member 57 are pushed back under the pressure of the spring 41.

The spring 55 tensioned between the two bushes 50 and 51 serves to damp shocks which the inertia member 57 exerts on the sleeve 43 during transport and during the handling of the projectile and which cause the end face 43a of the inertial sleeve 43 to strike against the bottom of the slide 9. This shock absorption prevents the extension 45 of the sleeve 43 from being plastically deformed in the vicinity of its end face 43a and the striker pin 28 no longer being able to pass through the bore in the extension 45 of the sleeve to contact the primer 13 on impact of the projectile.

The construction of the base fuse as a second embodiment is as follows:

According to FIGURES 2 and 3, a fuse body 70 of the base fuse is fitted into a fuse casing 71 and gripped from behind by the fuse base 73 which is screwed into the fuse casing 71 and which abuts against the shoulder 74 of the fuse body 70. A sleeve 76, which contains the booster charge 75, is screwed on to the front end of the fuse casing 71 and a cap 79 which holds the propagation charge 78 is inserted in a central bore taken through the cover 77 of the fuse casing 71.

Movably mounted in a groove cut in the body 70 of the fuse and directed transversely to the axis of the fuse is the detonator-cap slide 9 which contains the primer 13 in a bore 12 penetrating through it (FIGURE 3). The detonator-cap slide 9 is subject to the action of a leaf spring 15; furthermore, in the transport state, that is to say in the unarmed position of the fuse, the locking bush 16 mounted in the body 70 of the fuse is pushed forward as a bolt in front of the end face of the detonator-cap slide 9. This locking bush has already been described in detail with reference to the first embodiment.

The mode of operation of the base fuse described corresponds to the mode of operation of the point fuse. When the primer 13 is contacted, the explosive charge is caused to detonate through the propagation charge 78 and the booster charge 75,

I claim:

1. In a projectile, an impact fuze comprising a casing, a firing pin displaceable into a safety position and an armed position, a first spring urging said firing pin into said armed position, a safety element displaceable into a first and into a second position, a slide movable from a safety position to an arming position, said slide when in safety position preventing a displacement of said safety element into said second position, locking means cooperating with said firing pin which in the first position of said safety element hold said firing pin in safety position and which locking means in said second position of said safety element release said firing pin, a conical surface in said casing, an inertia body cooperating with said conical surface so that during a deceleration of the projectile transversely to the projectile axis said body is displaced on said conical surface in the direction of the projectile axis, a second spring located between said inertia body and said safety element, said inertia body being supported via said second spring on said safety element when in said first position and said inertia body during an axial and radial deceleration of said projectile when said slide is in arming position displacing said safety element against the force of said first spring from said first to said second position for releasing said firing pin and when said slide is in safety position pressing together said second spring.

2. In a projectile, an impact fuze comprising a casing, a first spring in said casing, a firing pin subject to the pressure of said spring having a safety position and an armed position, locking means to hold said firing pin in said safety position, two sleeves located one behind the other for displacement in said casing, having a first position in which both sleeves are forward in said casing, a second position in which both sleeves are to the rear in said casing and a third position in which one sleeve is forward and the other sleeve is to the rear in said housing, said rear sleeve being subject to the pressure of said spring tending to urge said rear sleeve towards the rear of said casing and to displace said firing pin into armed position, said sleeves being in said second position after the projectile has been fired, an inertia member which can be deflected transversely to the axis of the projectile and against which said rear sleeve bears under said spring pressure, said inertia member displacing both of said sleeves into said first position in the event of a resistance acting on the projectile transversely to the axis of the projectile, a holding member against which said locking means hold said firing pin in said safety position which is held in one direction between said inertia member and said rear sleeve, said locking means being secured by said front sleeve when said two sleeves are in said second 3,410,215 5 6 position and by said rear sleeve when said sleeves are in References Cited said first position, and said locking means being released UNITED STATES PATENTS when said sleeves are in said third position and a second spring between said inertia member and said rear sleeve. 5021348 8/1893 Clark 102-43 3. An impact fuze as set forth in claim 2 wherein two 5 2999461 9/1961 Apotheloz at X bushes are provided displaceable with respect to one an- 3,270,670 9/1966 Glfeme other in which said second spring is mounted. 1,305,398 7/1919 Mldgley 4. An impact fuze as claimed in claim 3 wherein the force of said second spring is greater than the force of BENJAMIN BORCHELT Pr'mary Exammer' said first spring acting on said rear sleeve. 10 G. H. GLANZMAN, Assistant Examiner. 

